Many enterprises store the same electronic data in more than one location. Reasons for this include improving the security and availability of this information in the event of computer outage, malfunction or disaster, as well as the ability for multiple entities and applications to manage the same information independently. As a consequence, when data changes in one data source it often needs to be copied to one or more secondary data sources, through a variety of possible mechanisms, including data replication. There are a number of challenges associated with data replication. For example, it is important to be able to independently verify that a replication mechanism is accurate. That is, it is important to confirm that data that should be copied from one location to another is indeed copied. When data sources are out of synchronization (i.e., asynchronous), it is important to re-synchronize them as efficiently as possible. These comparison and re-synchronization activities need to be performed in the context of the following constraints: high activity/rate of change in the data source, a dynamic environment in which there is no opportunity to turn off the application or database to perform a static comparison, and geographic separation accompanied by limited bandwidth between data sources.
In view of the foregoing, it would be highly desirable to provide an improved technique for data comparison and re-synchronization operations.